The invention relates to a method and a device for ascertaining a traffic status.
Data which are generated by vehicles, which are currently participating in a traffic situation, are used for current and reliable provision of items of traffic information. These vehicles acquire and transmit so-called floating car data (FCD). In an FCD system, predominantly a GPS receiver and a mobile wireless connection of the vehicle are used for the acquisition of the data. In an XFCD system (extended floating car data), data of all or a plurality of driver assistance systems are taken into consideration. Inter alia, the state of the road and the traffic flow can thus also be acquired, as well as situation-related traffic impairments.
The object on which the invention is based is to provide a method and a corresponding device that allow reliable ascertainment and optionally reliable provision of traffic status data.
The object is achieved by the features of the independent patent claims. Advantageous refinements of the invention are characterized in the dependent claims.
The invention is distinguished by a method and a corresponding device for ascertaining traffic status data. When it is recognized that a vehicle participates in a traffic flow, a speed of the vehicle is acquired multiple times at predefined time intervals. The respective acquired speed is assigned to a first speed range, when the respective acquired speed of the vehicle is greater than at least one predefined speed threshold. Furthermore, a first count is increased when the respective acquired speed is assigned to the first speed range. When the respective acquired speed of the vehicle is less than the at least one speed threshold, the respective acquired speed is assigned to a second speed range and a second count is increased, wherein a holding phase is recognized while the respective acquired speed, once or multiple times in succession, has a speed value in a predefined range around the value zero. During the recognized holding phase, the acquired speeds having the speed value in the predefined range around the value zero are not considered, for a predefined non-consideration number of speed acquisition periods, with respect to the adaptation of the second count. A first traffic status, which represents flowing traffic, is recognized when the first count exceeds a predefined first limiting value before the second count exceeds a predefined second limiting value. A second traffic status, which represents traffic congestion, is recognized when the second count first exceeds the predefined second limiting value before the first count exceeds the predefined first limiting value.
This advantageously allows precise and current ascertainment of the respective traffic status. The progressive ascertainment of the first count and the second count can provide a contribution to improving reliability of the traffic status recognition. It allows it to be reliably recognized whether traffic congestion is present or whether, for example, congestion-free further travel is possible. The at least partial non-consideration of the acquired speeds during the holding phases of the vehicle for the non-consideration number of speed acquisition periods allows frequent holding times, in particular in urban regions, which are not caused by congestion, but rather, for example, are caused by waiting times of traffic signal facilities and/or intersections and normal traffic conditions in a city in particular, can be filtered out. These holding times at traffic signal systems and/or intersection regions are thus not incorrectly recognized as a disturbance, which is caused by traffic congestion. Supplementary intersection region recognition is not necessary.
In each case an acquired current speed can advantageously be used for the ascertainment of the traffic status data. The traffic status recognition can nonetheless be performed sufficiently reliably. Ascertainment of an average speed and provision of data connected thereto are not necessary.
Fundamentally, the first count can alternatively also be decreased if the respective acquired speed is assigned to the first speed range. This then also applies correspondingly for the second count. In this case, conditions which comprise the first or second count are opposite.
In an advantageous embodiment, the acquired speed is an acquired current actual speed of the vehicle. This allows both computing power and also a memory requirement to be reduced.
In a further advantageous embodiment, the non-consideration number per holding phase is fixedly predefined. This allows very simple recognition as to whether the first or the second traffic status is present.
In a further advantageous embodiment, the non-consideration number is ascertained depending on a duration of at least one preceding holding phase of the vehicle and/or depending on a time span which lies between the at least one preceding holding phase and the holding phase. This can provide a contribution to increasing reliability of the traffic status recognition.
In a further advantageous embodiment, the non-consideration number is ascertained depending on a turn signal status of the vehicle and/or a recognized lane, on which the vehicle is located. This can provide a contribution to improving reliability of the traffic status recognition. In particular, it can thus be taken into consideration that a holding phase at a traffic signal system and/or at an intersection is lengthened when the vehicle wishes to turn off, for example, in particular when the vehicle wishes to turn to the left in the case of prescribed right-hand traffic. The vehicle can have a position ascertainment unit, which is implemented to acquire a current position of the vehicle and to assign this position to a lane of a road. The acquired turn signal status can be acquired and provided, for example, by a central control unit.
In a further advantageous embodiment, depending on an acquired position of the vehicle and predefined digital roadmap data, a road and/or a road type is/are ascertained, on which the vehicle is currently moving, and depending on the road or the road type, respectively, the at least one speed threshold is ascertained. The at least one speed threshold can be ascertained simply and in a manner tailored to a driving situation.
In a further advantageous embodiment, when it is recognized that the vehicle is subjected to at least one traffic influence, which results or which is expected to result in a reduction of the speed of the vehicle in relation to a normal speed without such traffic influences, the at least one speed threshold is ascertained depending on the at least one traffic influence. This enables boundary conditions, for example, a weather and/or a road layout, to be taken into consideration when ascertaining the at least one speed threshold, and enables the at least one speed threshold to be adapted to the boundary condition.
In a further advantageous embodiment, the non-consideration number is ascertained depending on an assignment of the current position of the vehicle to an urban or rural region. In particular, the non-consideration number can be fixedly predefined for rural regions and can have the value zero.
In a further advantageous embodiment, dependent on the road or the road type, an upper speed threshold and a lower speed threshold are ascertained. The acquired speed is assigned to the first speed range if the respective acquired speed of the vehicle is greater than the upper speed threshold. If the respective acquired speed of the vehicle is less than the lower speed threshold, the acquired speed is assigned to the second speed range. This can allow better estimation of the traffic situation by way of different speed classes. Thus, falling below the lower speed threshold is an indication that the vehicle is moving or stationary in congestion. A speed of the vehicle which lies in the range between the lower and the upper speed threshold is an indication that the vehicle is moving in a rather undefined status between congestion and free travel. A speed of the vehicle which is higher than the upper speed threshold is finally an indication that the relevant vehicle has free travel. By way of this classification, it is possible to weigh the mentioned statuses differently. This in turn enables substantially reliable congestion recognition also in the case of multiple statuses, which occur during the observation time to decide whether or not congestion is present. Alternatively, the movement or the speed of the vehicle can also be classified in more than three speed classes or speed ranges, respectively. This can be reasonable in particular if it is not only to be differentiated whether or not a vehicle is located in congestion, but rather also it is to be ascertained which points of the congestion are traveled at which speeds on average.
In a further advantageous embodiment, the acquired speed is assigned to the second speed range if it is less than the upper speed threshold and is greater than the lower speed threshold and if the immediately previously acquired speed is assigned to the second speed range. In contrast, the acquired speed is assigned to the first speed range if it is less than the upper speed threshold and is greater than the lower speed threshold and if the immediately previously acquired speed is assigned to the first speed range. This advantageously allows a reliability of a traffic status recognition to be improved. In this manner, it is possible to prevent the first traffic status and the second traffic status from being considered to be recognized alternately as a result of short-term changes of the acquired speeds within only short time intervals. In particular, this allows an acquired current actual speed of the vehicle to be used for the ascertainment of the traffic status data in each case. The traffic status recognition can be performed with sufficient reliability in spite of frequent short-term changes of the current actual speed. An ascertainment of an average speed and a provision of data connected thereto are not necessary.
In a further advantageous embodiment, the acquired speed is equally assigned to the first and second speed range if it is less than the upper speed threshold and is greater than the lower speed threshold. This advantageously allows reliability of traffic status recognition to be improved. In this manner, it is possible to avoid the first traffic status and the second traffic status being recognized alternately as a result of short-term changes of the acquired speeds within only short time intervals.
In a further advantageous embodiment, the acquired speed is assigned to neither the first nor the second speed range when it is less than the upper speed threshold and is greater than the lower speed threshold.
In a further advantageous embodiment, when, upon the respective ascertainment of the second count, the second count exceeds a predefined second threshold value, a predefined first initialization value is assigned to the first count. When, upon the respective ascertainment of the first count, the first count exceeds a predefined first threshold value, a predefined second initialization value is assigned to the second count. This allows a reset of the first and second counts in particular if the corresponding count remains unchanged for a longer time. The first and second initialization values can be zero, for example.
In a further advantageous embodiment, when a change from the first traffic status to the second traffic status or vice versa is recognized and therefore the second traffic status is newly recognized or the first traffic status is newly recognized, respectively, it is checked whether the newly recognized second traffic status or the newly recognized first traffic status, respectively, was already communicated to the vehicle. If it was not already communicated to the vehicle, a data set is ascertained, which describes the changed traffic status. This data set is transmitted to a central unit. Advantageously, this allows an event-oriented and non-redundant data transmission to an institution which reconstructs and displays the traffic situation, for example, a traffic data central office. If the information in the vehicle is already known, a recognized changed traffic status is not ascertained. In this manner, it is possible to correct a traffic report which was transmitted by a service provider to the vehicle. The costs of the data transmission can be kept low.
Exemplary embodiments are explained hereafter on the basis of the schematic drawings.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.
Elements of identical construction or function are provided with identical reference signs in all of the figures.